问题
选择题
The little boy is dirty from head to foot because he ________ in the mud all morning.
A．has played
B．is playing
C．has been playing
D．was playing
答案
C
由“…is dirty”和“all morning”可知，小孩一直在玩。过去的动作一直延续到现在并且还在进行应用现在完成进行时表示。